It is known in the relevant art that transoceanic shipping containers and other devices used to transport goods (hereinafter, “containers”) can be equipped with tracking devices to track movement of the container through distribution channels and to monitor various operating conditions of the container during transportation. Additionally, these tracking devices are equipped with various sensors to gather information about the operating conditions of the container and include wireless transmitters to communicate the gathered information with a backend system. The backend system conventionally is an industrial class computer (or “server”) residing in a stationary position and its location is usually terrestrial. As a consequence, the backend server is not in transit with the container. Examples of information communicated by tracking devices to the backend system include: reporting notable events (e.g. loading and unloading the container), alarms regarding certain conditions that have occurred (e.g. server temperature fluctuations) or reporting a current position. The communication channels typically used by the tracking devices to communicate with the backend system are based on wireless technologies that facilitate long-range communications, e.g. where the effective communication range is measured in kilometers. Examples of such long-range communication methods include Global System for Mobile communication protocol (“GSM”), wide area network protocols (“WAN”), and protocols based in the International Telecommunication Union IMT-2000 standard (“3G”). Additionally, tracking devices may use satellite technologies to communicate with the backend system.
Power management is a significant challenge when designing a tracking device, because these devices lack an external power source. It is well known in the relevant art that a major contributor to power consumption includes any power requirements needed for operating a satellite navigation system transceiver device (e.g., transceivers capable of communicating with the Global Positioning System, or “GPS” transceivers) used in the detection of signals for determining a containers geographical location and in the wireless transmission of position information. For various reasons, when the tracking device is on-board a transoceanic shipping vessel, the tracking device is sometimes unable to detect a GPS signal or communicate with the backend system via long-range communication mechanisms due to interference (e.g. the structure of a shipping vessel, and placement of the containers therein, causes interference such that the transceivers of each tracking device are unable to properly transmit or receive over long distances). Consequently, those functions are usually disabled to save power and enabled when the container is unloaded from the vessel.
To automate saving power by disabling the GPS subsystem, tracking devices will disable the communication channel based on passage through “geofences” (e.g. a loading or unloading zone) during transport to a predetermined destination and according to a predetermined ocean trip duration. Both the ocean trip duration and the geofences, and hence when the tracking device will disable its communications channel, are configured prior to loading time.
As a consequence, the current system is rigid because the ocean trip duration must be estimated when the trip is scheduled and cannot be modified during transit. For example, the tracking devices will not be reconfigured when the vessel's transoceanic route is modified. Since the tracking devices will remain asleep during an unscheduled trans-shipment modification, important tracking data is lost. This rigidity in the current system is considered a major drawback of the power saving process.
It would be desirable to provide a method for optimizing the power consumption of tracking devices coupled to containers aboard these transoceanic shipping vessels, while accommodating unexpected changes to the shipping route.